Some clarificaation…. a while back you helped me write a testing framework…here
is the code:
get_all_tests(Tests) :-
setof(Line-Name, get_one_test(Name, Line), Tests).
get_one_test(Name, Line) :-
current_predicate(Name/0),
atom_concat('test_', _, Name),
predicate_property(Name, prolog_line(Line)).
It uses ‘pairs’ as I understand them, using the ‘-‘ to combine the key and
value, so in your response, what is ‘=‘ doing in this context in the list of
flags????
Just when I thouthgh I was beginning to understand! LMAO
Thanks once again,
Sean.
On 9 Apr 2014, at 09:18, Daniel Diaz <[email protected]> wrote:
> Hello Sean,
>
> you can do this with your own loop or use findall like this:
>
> flag(public, 0x0001).
> flag(final, 0x0010).
> flag(super, 0x0020).
> flag(interface, 0x0200).
> flag(abstract, 0x0400).
> flag(synthetic, 0x1000).
> flag(annotation, 0x2000).
> flag(enum, 0x4000).
>
>
> get_java_flags(Value, Flags) :-
> findall(Name, has_flag(Value, Name), Flags).
>
>
> has_flag(Value, Name) :-
> flag(Name, Mask),
> Value /\ Mask =\= 0.
>
>
> then call it with:
>
> | ?- get_java_flags(0x421, Flags).
>
> Flags = [public,super,abstract]
>
> I have detailed a bit to be more comprehensive: the has_flag/2 predicate
> could be inlined inside the findall surrounding with ().
>
> If you prefer to have the flags as a parameter pass them as a list and use
> member to handle backtracking (done by get_flags/3 here):
>
> get_java_flags(Value, Flags) :-
> FlagNames = [public = 0x0001,
> final = 0x0010,
> super = 0x0020,
> interface = 0x0200,
> abstract = 0x0400,
> synthetic = 0x1000,
> annotation = 0x2000,
> enum = 0x4000],
> get_flags(FlagNames, Value, Flags).
>
>
>
> get_flags(FlagNames, Value, Flags) :-
> findall(Name, has_flag(FlagNames, Value, Name), Flags).
>
> has_flag(NameFlags, Value, Name) :-
> member(Name=Mask, NameFlags),
> Value /\ Mask =\= 0.
>
>
> Daniel
>
> Le 09/04/2014 01:02, Sean Charles a écrit :
>> Hello list,
>>
>> I have almost completed a predicate called ‘jread’ which parses a Java
>> .class file into a term that will allow me to create a database of all of
>> the methods, fields, superclass and interfaces for that class and ultimately
>> create a database for a complete “android.jar” file of any required API
>> level.
>>
>> I am, for educational purposes and my own learning, trying to build a system
>> like Hoogle/Hayoo for Android. I do a lot of Android and I wanted to create
>> a sytem I can wire into Emacs/IntelliJ or anything for that matter, a simple
>> HTTP server that can supply a list of methods that have a certain type
>> signature using a si mple query language. Searching by types it very very
>> useful when using Haskell and I wanted to improve my Prolog so I figured why
>> not do something like that in GNU Prolog? I have already started a simple
>> HTTP library in pure GNU Prolog as well but this comes first now.
>>
>> Progress so far is good…if I run it like this from a folder containing the
>> unpacked android.jar file...
>>
>> | ?- jread('javax/net/SocketFactory.class',X).
>>
>> X =
>> javaclass(super('java/lang/Object'),class('javax/net/SocketFactory'),implements([]),
>> methods([method(access_flags(4),name('<init>'),returns('()V'),[attr(9,
>> [0,3,0,1,0,0,0,14,42,183,0,1,187,0,2,89,18,3,183,0,4,191,0,0,0,2,0,10,0,0,0,6,0,1,0,0,0
>> ,4,0,11,0,0,0,12,0,1,0,0,0,14,0,12,0,13,0,0])]),method(access_flags(41),name(getDefault)
>> ,returns('()Ljavax/net/SocketFactory;'),attr(9,0,3,0,0,0,0,0,10,187,0,2,89,18,3,183,0,4,
>> 191,0,0,0,1,0,10,0,0,0,6,0,1,0,0,0,5])]),method(access_flags(1),name(createSocket),
>> returns('()Ljava/net/Socket;'),[attr(9,0,3,0,1,0,0,0,10,187,0,2,89,18,3,183,0,4,191,
>> 0,0,0,2,0,10,0,0,0,6,0,1,0,0,0,6,0,11,0,0,0,12,0,1,0,0,0,10,0,12,0,13,0,0]),
>> attr(18,0,1,0,19])]),method(access_flags(1025),name(createSocket),
>> returns('(Ljava/lang/String;I)Ljava/net/Socket;'),[attr(18,[0,2,0,19,0,21])]),
>> method(access_flags(1025),name(createSocket),
>> returns('(Ljava/lang/String;ILjava/net/InetAddress;I)Ljava/net/Socket;’),
>> [attr(18,[0,2,0,19,0,21])]),method(access_flags(1025),name(createSocket),
>> returns('(Ljava/net/InetAddress;I)Ljava/net/Socket;’),[attr(18[0,1,0,19])]),method(access_flags(1025),name(createSocket),
>> returns('(Ljava/net/InetAddress;ILjava/net/InetAddress;I)Ljava/net/Socket;'),[attr(18,[0,1,0,19])])]))
>> ?
>>
>> The place I am at now is decoding the bit flags for the class (and
>> eventually the methods etc) into a term.
>>
>> A typical value would be “1057” decimal, 0x421, this contains the flags:
>>
>> ACC_PUBLIC 0x0001 Declared public; may be accessed from outside its
>> package.
>> ACC_FINAL 0x0010 Declared final; no subclasses allowed.
>> ACC_SUPER 0x0020 Treat superclass methods specially when invoked by the
>> invokespecial instruction.
>> ACC_INTERFACE 0x0200 Is an interface, not a class.
>> ACC_ABSTRACT 0x0400 Declared abstract; must not be instantiated.
>> ACC_SYNTHETIC 0x1000 Declared synthetic; not present in the source
>> code.
>> ACC_ANNOTATION 0x2000 Declared as an annotation type.
>> ACC_ENUM 0x4000 Declared as an enum type.
>>
>> So you can see that 0x421 means “ACC_PUBLIC, ACC_SUPER and ACC_ABSTRACT”. I
>> would like to produce a term something like this:
>>
>> access_flags(public,super,abstract)
>>
>> It’s not that I don’t know how to do it or that I can’t do it but I am not
>> sure what is the *most elegant* way to do it in Prolog! Heaven knows I have
>> written bit shifting loops to test for flags in a dozen languages but not in
>> Prolog.
>>
>> So, there’s the challenge, what is the most elegant way to turn a list of
>> bits into a list of atom terms. Ideally I would make the list of atoms a
>> parameter so that I can reuse it for the other flag based values.
>>
>> Consider the gauntlet thrown! In the meantime I am continuing to research
>> the possibilities for myself. I will of course put it all on GitHub along
>> with my Redis client. I may even create a Redis database with the
>> information!
>>
>> :)
>> Sean.
>>
>>
>
>
> --
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